Arcuate magnet having polar-anisotropic orientation, and method and molding die for producing it

A method for producing an arcuate magnet having polar-anisotropic orientation, using a die apparatus comprising

• a die made of non-magnetic cemented carbide, which is arranged in a parallel magnetic field generated by a pair of opposing magnetic field coils;
• an arcuate-cross-sectional cavity having an inner arcuate wall, an outer arcuate wall and two side walls, which is disposed in said die;
• a central ferromagnetic body arranged on the side of the outer arcuate wall of said cavity with distance from said cavity;
• and
• a pair of side ferromagnetic bodies symmetrically arranged on both side wall sides of said cavity with distance from said cavity;
• said cavity being arranged such that its radial direction at a circumferential center thereof is identical with the direction of said parallel magnetic field;
• the width of said central ferromagnetic body being smaller than the width of said cavity in a direction perpendicular to said parallel magnetic field, when viewed from above;
• and
• a pair of said side ferromagnetic bodies being arranged such that said cavity is positioned in a region sandwiched by a pair of said side ferromagnetic bodies;
• magnetic powder charged into said cavity being compression-molded in said parallel magnetic field.